Examples of structures of a cover unit of a work machine include a double-panel structure including an outer panel and an inner panel, wherein the inner panel has a plurality of recessed portions, and the outer panel and the inner panel are affixed to each other by bonding the recessed portions of the inner panel to the outer panel and hemming the peripheral edge of the outer panel. Hinges are directly attached to a raised portion, which is the portion bulging relative to the recessed portions (e.g. See Japanese Laid-open Patent Publication No. 9-228412 (pages 2 to 3, and FIGS. 2 to 8)).
The conventional cover unit with the double-panel structure described above presents the possibility of insufficient strength, because the hinges are directly welded to a flat portion of the raised portion of the inner panel.
Furthermore, it is necessary to ensure availability of a large flat portion in order to provide the inner panel or the like with welding margins, making it difficult to add a reinforcing structure shaped with such irregularities as raised and recessed portions.
In order to solve the above problems, an object of the invention is to provide a door panel that has a double-panel structure including an outer panel and an inner panel and is capable of ensuring sufficient strength at portions where hinges are attached. Another object of the invention is to provide a door panel that enables at least apart of the periphery of the portions where the hinges are attached to be easily provided with a reinforcing structure.